0:00
It's the 365 days of Astronomy Podcast coming in 3, 2, 1.
0:23
There are likely to be 2 million lunar impact craters, analysis of Mars orbiter images
0:29
with AI, has cataloged some 94 million Martian impact craters with diameters of 100 meters
0:37
However, on our home planet, because of erosion by wind and water, and that three-quarters
0:42
of the world is covered with water, we have identified only about 200 impact craters.
0:47
Thus a paper entitled The Silver Bullet, New Evidence for a Hyper-Velocity Impact
0:53
Origin for the Silver Pit Crater, published in the journal Nature Communications, has stirred
0:58
up considerable interest among impact craters sleuths.
1:02
The Silver Pit Crater, discovered in 2002, is about 1.8 miles wide and lies some 766 yards
1:10
below the sea floor.
1:12
It is located in the North Sea approximately 80 miles from the Yorkshire coastline.
1:17
In their paper, Dr. Yusadine Nicholson, from Heret-Watt University and his team of nine co-authors,
1:24
analyzed 3D seismic imaging and drill cuttings from a 1980s oil well to make a convincing
1:30
case that the Silver Pit Crater was produced by the impact of a 1.5 football field diameter
1:37
asteroid approximately 45 million years ago.
1:40
The crucial piece of evidence is the presence of rare, shocked, quartz and fellspar crystals
1:46
only produced by the extreme temperatures and pressures of a hyper-velocity impact
1:51
at the same depths as the crater floor.
1:54
The event itself was an awesome natural spectacle caused when the asteroid traveling at 9 miles
1:59
per second slammed into the ocean floor, producing a mile high wall of rock and seawater
2:06
and a 30-story high tsunami.
2:08
Fortunately, asteroid hunters have not found a dangerous asteroid like this one heading
2:15
Now travelers in the night, this is Dr. Al Grower, stay tuned.
2:24
In a recent 60-day period, asteroid hunters tracked 24 space rocks which came closer than
2:31
Half of them were smaller than a London double-decker bus.
2:35
The smallest has a diameter about the height of a human being, while the largest has a
2:39
diameter about three-quarters of the wingspan of a 747.
2:44
Two of them, both smaller than a compact car, came closer to humanity than the communication
2:51
An object of their size enters the Earth's atmosphere every few months, creating a
2:56
light and sound show.
2:58
The largest and rarest visitor was 2025 RM1.
3:02
It has a diameter about half the size of a football field and was discovered by the
3:07
Atlas Group in Hawaii after it had passed about 60,000 miles from the Earth's surface.
3:14
According to the Earth Impact's calculator program, from the Imperial College of London
3:19
at Purdue University, an object of size of 2025 RM1 enters the Earth's atmosphere
3:25
approximately once every 460 years, begins to break up at an altitude of 222,000 feet
3:32
and burst into fragments at an altitude of about 44,000 feet.
3:37
It would not make a crater, but it is likely that large fragments traveling at three miles
3:42
per second would strike the surface.
3:44
It would create a spectacular light and sound event, a noise as loud as heavy traffic,
3:50
and an air blast that would likely shatter windows.
3:54
My team, the University of Arizona's Ketalina Sky Survey, operates five telescopes in the
3:59
mountains around Tucson, Arizona.
4:01
Our goal is to find objects like 2025 RM1, which are on an impact trajectory with our
4:08
home planet in advance, so that people in the affected area can be worn to stay away from
4:16
For travelers in the night, this is Dr. Al Grower.
4:20
You are listening to the 365 Days of Astronomy Podcast.
4:39
The 365 Days of Astronomy Podcast is produced by the Planetary Science Institute.
4:46
Audio post-production is by me, Richard Drum.
4:49
Creative management is by Aviva Yamani, and hosting is donated by LibSyn.com.
4:55
This content is released under a Creative Commons Attribution Non-Commercial 4.0 International
5:03
Please share what you love, but don't sell what's free.
5:07
This show is made possible thanks to the generous donations of people like you.
5:11
Please consider supporting our show on patreon.com, forward slash CosmoQuestX, and get access
5:20
Without your passion and contribution, we won't be able to share the stories and inspire
5:26
We invite you to join our community of storytellers and share your voice with listeners worldwide.
5:33
As we wrap up today's episode, we're looking forward to unraveling more stories from
5:39
With every new discovery from ground-based and space-based observatories and each milestone
5:44
in space exploration, we come closer to understanding the cosmos and our place within
5:51
Until next time, let the stars guide your curiosity.